3.7 A 7Gb/s rapid on/off embedded-clock serial-link transceiver with 20ns power-on time, 740μW off-state power for energy-proportional links in 65nm CMOS

Energy-proportional operation of serial links is imperative for realizing energy-efficient data centers and low-power mobile interfaces such as MIPI. Burst-mode communication, where the link is powered-off when idle and powered-on when needed, achieves energy proportional operation. Ideally, a burst mode link must be turned on/off in zero time, must consume zero power in the off-state and must incur zero energy overhead while making on/off transitions. However, these requirements are difficult to meet in practice and as a consequence, the efficacy of burst mode communication in achieving energy proportional operation is reduced. The main challenges in achieving small power-on time and off-state power include the design of fast-locking PLLs, CDRs and achieving fast settling of bias node voltages. In this paper, we present a complete 7Gb/s energy-proportional embedded-clock transceiver that achieves less than 20ns power-on time while consuming 63.7mW on-state power, 0.74mW off-state power and 1.2nJ of total transition energy penalty per burst.